The present invention relates to a connector for a discharge lamp, especially for a motor vehicle.
Conventionally, such a connector includes a base which is adapted to receive the end cap of the discharge lamp and which has in its interior two metallic contact elements which are connected to a discharge lamp power supply circuit or ballast. When a lamp is in place in the connector, its electrodes are connected to the supply circuit through these contacts.
It can happen that a voltage is applied to the metallic contacts by the starting module of the supply circuit, even when no discharge lamp is fitted in the connector. Arcs are then set up within the connector, and this can involve substantial damage to the latter. In this connection the arcs can reach very high power.
Various solutions have previously been proposed in order to overcome this drawback. In particular, connectors have been proposed which have an internal resilient contactor which only closes the power supply circuit on the contacts when it is pushed by the fitting of a discharge lamp in the connector.
Solutions have also been proposed in which the supply circuit for the lamp only closes on the contacts through the low tension cap skirt of the lamp.
In addition, connectors have been proposed in which their internal metallic contacts are, in the absence of any lamp, capped by an electrically insulating removable element which is pushed away when a lamp is fitted in the connector.
These various solutions do however prove complicated to achieve, because they call for the incorporation of various electrical connections within the connector. They can also give rise to reliability problems.
An object of the invention is to propose a solution which does not have the above mentioned disadvantages.
According to the invention, a connector for a discharge lamp, especially for a motor vehicle, comprising at least two electrical contacts for power supply to the high tension and low tension electrodes, respectively, of the said lamp, is characterised in that it includes means which, for arcs through which the power supply module to which the connector is connected is discharged when it applies a voltage to the said contacts with no lamp in place in the connector, impose a preferential path on the arc other than a direct path between the said contacts.
Such a connector may with advantage also have the various features of the invention set out below, either individually or in any technically possible combination:
it includes means through which the current corresponding to the said arcs flows, and which limit the intensity of the said arcs;
it includes a metallic element the disposition of which contributes to the imposition on the arcs of a preferential path other than a direct path between the contacts;
a metallic element is connected to one of the electrical contacts such that the electrical arcs traverse it when the arcs are established in their preferential path;
the said metallic element is such that the preferential path of the arcs is between the said metallic element and the contact to which it is not connected;
a metallic element is such that it lies close to the contact to which it is not connected, when no lamp is in place in the connector;
a metallic element is such that it is closer to the contact to which it is not connected than to the other contact, when no lamp is in place on the connector;
a said metallic element is connected to the contact supplying the low tension electrode of the lamp when a lamp is fitted in the connector;
one metallic element is a contact designed to supply a low tension electrode of the lamp;
a metallic element is movable between a closed circuit position into which it is displaced by insertion of the lamp and an open circuit position in which it is maintained elastically when no lamp is fitted;
a resilient lug extends substantially radially within the connector from a wall of the latter towards the contact which is adapted to supply the high tension electrode of the lamp;
it includes at least two metallic elements, one of which is connected to the low tension electrode and the other to the high tension electrode, such that the electrical arcs are established in a preferential path between the two said metallic elements.
Further features and advantages of the invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.